1. Field of the Invention
The present invention relates to a medical dressing containing an antimicrobial agent, a sponge formed from such a dressing, and methods of fabricating such a medical dressing and sponge.
2. Brief Description of Art
Medical dressings have long been used to protect and aid in the healing of wounds. Various forms and constructions of such medical dressings are known in the art. For instance, U.S. Pat. No. 4,211,227, incorporated herein by reference, discloses a nonwoven surgical sponge material comprising a layered fabric having an inner core or a substantially hydrophilic material disposed adjacent at least one outer or surface layer, or between a pair of outer layers, of a substantially hydrophobic material. The sponge material is bonded by passing the material through rolls engraved in a pattern of lands and grooves such that a repeating pattern of three degrees of compression are imposed on the material.
U.S. Pat. No. 6,369,289, incorporated herein by reference, further discloses the use of a cellulosic bandage in a method for covering an open wound by contacting the wound with the bandage having a calculated amount of antimicrobial agent. The cellulosic bandage may be prepared by providing at least one rolled beam of cellulosic material onto a perforated drum, inserting the beam of material into an enclosed vessel, adding antimicrobial agent into the vessel, and circulating the antimicrobial agent for a predetermined period of time.
The use of certain kinds of antimicrobial agents is also known in the art. U.S. Pat. No. 4,655,756, for example, relates to a non-woven material treated with a linear polymeric biguanide having a defined formula, or a mixture of, e.g., polyhexamethylene biguanide (hereafter “PHMB”) dihydrochlorides with defined number average molecular weights. The polymeric biguanide may be present at a concentration of from 500 to 5000 ppm and the non-woven material may be in the form of an article for the collection of human body emissions.
Other types of antimicrobial agents are also known. For example, U.S. Pat. No. 5,707,736 discloses a dry, disposable, polymeric product having sustained-release antimicrobial activity formed from a polymeric material having an amine salt antimicrobial agent incorporated therein. The polymeric material may be in the form of fibers, sheets, films, and other stable woven, nonwoven and knitted materials. The antimicrobial agents include, e.g., chlorhexidine gluconate and chlorhexidine hydrochloride.
Additional components, such as adhesives, are also known as components of medical dressings. One such surgical dressing is described in U.S. Pat. No. 4,643,180, wherein the dressing comprises a sheet of polymeric film coated on one side with a water based adhesive of defined thickness which includes an antimicrobial agent deposited on the body facing surface of the adhesive.
U.S. Pat. No. 4,643,181 also describes a surgical dressing and a process for making a surgical dressing. The dressing comprises a substrate coated on one surface with a solvent-based skin contact adhesive of defined thickness, the adhesive having distributed therein particles of PHMB. The process involves mixing a defined aqueous solution of PHMB hydrochloride with a solvent which is compatible with the adhesive at a mixing speed of no more than 300 rpm, adding the mixture to an adhesive, applying the adhesive to a release surface in an amount of from 40 to 55 grams per square meter, drying the adhesive, and applying a substrate for the dressing to the adhesive.
U.S. Pat. No. 4,675,347 relates to an antimicrobial latex composition and a method of manufacturing a shaped article by repeatedly dipping an article into the composition and drying. The composition comprises, e.g., (1) at least one cationic latex component selected from a cationic natural rubber latex and a cationic synthetic polymer latex and (2) a cationic antimicrobial agent incorporated in the cationic latex (1).
U.S. Pat. No. 4,678,704 describes an impregnated fabric material comprising a fabric substrate to which has been bonded an active cationic impregnant along with an anionic indicator dye in combination with a further cationic component, wherein the dye bonds to the further cationic component more readily than to the substrate and the further cationic component competes with the impregnant for bonding to the dye. The cationic impregnant may be a polymeric biguanide, e.g., PHMB.
U.S. Pat. No. 4,837,079 relates to a method for making an antimicrobially active, non-woven web comprising the steps of forming an unbounded fibrous web, applying throughout the unbonded fibrous web an uncured binder and PHMB hydrochloride as an antimicrobial agent, the PHMB hydrochloride being substantive to the fibers of the web and to the binder when the web is either wet or dry to prevent the antimicrobial agent from substantially diffusing from the fibers or binder and being present in an amount effective to act as antimicrobial agent, and curing the binder to bind the fibers together to form an antimicrobially active, non-woven web. An antimicrobially active, non-woven web comprising bonded fibers, a binder distributed throughout the fibers in an amount effective to bind the fibers and PHMB hydrochloride which is substantially prevented from diffusing from the fibers or the binder is also disclosed. Further disclosed is a wet wiper that is substantially identical to the claimed web, but which additionally contains a substantially preservative free liquid.
U.S. Pat. No. 5,098,417 relates to a wound dressing for systemic administration of a physiologically- or biologically-active agent by controlled release of the agent into such wound. The wound dressing comprises a substrate in the form of a fabric or cloth, at least a portion of which is cellulosic, which has been chemically modified to convert hydroxyl groups in the cellulosic portion to ionic-adsorbing sites, an ionic form of a physiologically- or biologically-active agent (which includes antibacterial agents) adsorbed in the substrate. The ionic bonds hold the agent temporarily to the substrate for controlled release therefrom in proportion to the amount of exudate in contact with the substrate and are formed by adsorbing the agent on the substrate at room temperature. The ionic bonds are disassociated upon contact with body exudate from wounds thereby to release the physiologically- or biologically-active agent in an amount in proportion to the amount of exudate in contact with the substrate. Chlorhexidine is mentioned as one of the possible agents.
U.S. Pat. No. 5,141,803 relates to a moistened wipe for cleaning and delivering a cationic biocide comprising a flexible absorbent nonwoven substrate impregnated with an aqueous composition comprising defined amounts of potassium sorbate, citric acid, disodium ethylenediaminetetraacetate, a cationic biocide selected from a defined group which includes PHMB hydrochloride and the remainder water. The pH of the composition is from about 3.5 to about 4.5.
U.S. Pat. No. 5,156,843 relates to a composition of matter comprising a material provided with interstices having solid particles residing therein. The material is a member selected from the group consisting of joined fibers, woven fabric, non-woven fabric, paper, woven cloth, non-woven cloth, foamed plastic and sponge. The solid particles are from about one to about 100 microns in diameter and contain a substantially continuous network of pores open to the exterior of the particles, with a functional substance retained in the pores. The functional substance may be a biocidal substance that can prevent or retard bacterial, microbial, germ or fungal growth.
U.S. Pat. No. 5,498,416 relates to a process for protection of prostheses, implants and/or catheters, of temporary or permanent implantable materials against bacterial colonization and infection. An infection-resistant device capable of progressively releasing in aqueous medium an amount of an antibacterial substance fixed to the device, the amount being effective to prevent bacterial contamination of the device is disclosed. The device comprises a first coating from a solution in aqueous or organic solvent of a biguanide of a defined general formula (which defines monomeric compounds) and a second coating from a solution of the antibacterial substance, the second coating overlying the first coating, and the first coating ensuring adhesion of the antibacterial substance to the device. Illustrative devices are described in the paragraph beginning at column 2, line 60 and include urinary catheters, probes, vascular and intraarterial catheters, cardiacal valvular prostheses, arterial prostheses, cardiac simulators, orthopedic prostheses, ocular or dental implants, shunts that are connecting two segments of the circulatory system, and suture thread.
U.S. Pat. No. 5,700,742 relates to a method of treating a textile material to inhibit microbial growth which comprises applying to the textile material an oligo- or polymeric biguanide or salt thereof with an inorganic acid or an organic acid having a pK value above 4.5 followed by a strong organic acid having a pK value below 4.5 and free from any aliphatic or oxyalkylene chain containing 12 or more carbon atoms. A textile material treated in accordance with the claimed method is also disclosed.
U.S. Pat. No. 5,856,248 relates to cellulose fibers and products comprising cellulose fibers treated to absorb body secretions while substantially decreasing microbial growth, the fibers being chemically modified in a two-stage process comprising a first stage treatment with a water soluble salt of a transition metal and an alkali and a second stage treatment with a solution of a bisbiguanide compound, thereby forming a bond between the cellulose fibers, the transition metal and the bisbiguanide compound. The process may utilize a rinsing step to neutral pH between the two aforementioned stages.
U.S. Pat. No. 5,869,073 relates to a liquid composition for applying a non-leachable antimicrobial layer or coating on a surface, comprising a solution, dispersion or suspension of a biguanide polymer, a cross-linker reacted with the biguanide polymer to form an adduct, and an antimicrobial metal, metal salt (e.g. a silver salt) or metal complex, wherein the metal, metal salt or metal complex forms a complex with the adduct, and wherein the antimicrobial layer or coating does not release biocidal levels of leachables into a contacting solution.
U.S. Pat. No. 5,817,325 relates to an article of manufacture having disposed on a surface thereof a contact-killing, non-leaching antimicrobial coating which kills microorganisms upon contact. The coating comprises an organic polycationic polymer matrix immobilized on the surface having bound or complexed thereto a surface-accessible antimicrobial metallic material such that the antimicrobial material does not release biocidal amounts of elutables into the surrounding environment. The organic matrix may comprise a biguanide polymer, such as PHMB or a polymer containing a biguanide moiety.
U.S. Pat. No. 5,849,311 further relates to a contact-killing, non-leaching antimicrobial material, capable of killing microorganisms which come into contact with the material. The material comprises an organic polycationic polymer matrix having non-leachably bound or complexed thereto an antimicrobial metallic material, such that the antimicrobial material does not release biocidal amounts of elutables into the surrounding environment. The polycationic material may be PHMB or a polymer containing a biguanide moiety.
U.S. Pat. No. 5,886,048 relates to a method of treating tumor disease in a human or animal with a therapeutically effective amount of PHMB or salt thereof.
U.S. Pat. No. 5,985,931 relates to an antimicrobial composition comprising defined amounts of PHMB, a quaternary ammonium compound; and parachlorometaxylenol wherein the combination of the three components is said to exhibit effective antimicrobial activity.
U.S. Pat. No. 5,990,174 relates to a method for improving haze formation and storage stability of an antimicrobial composition consisting of water and from 5 to 25% by weight of defined linear polymeric biguanide oligomers. The method comprises adjusting the pH of the aqueous antimicrobial composition to at least 0.1 and less than 5 as determined using an indicator thereby improving the resistance to haze formation and storage stability of the aqueous antimicrobial composition when compared with a corresponding composition at higher pH. Particular concentration and pH limitations are also disclosed.
U.S. Pat. No. 5,993,840 relates to a composition comprising a non-woven material containing a mixture of polymeric biguanides subject to desorbtion when the non-woven material is wetted by urine; and an anionic polymer which is substantially insoluble in urine. The anionic polymer functions to retain the biguanides on the material when contacted by urine. A process for forming an absorbent layer and a method of reducing the loss of antimicrobial biguanide, wherein both include the anionic polymer, are disclosed.
European Patent Application No. 136900 discloses the application of PHMB to a surgical drape comprising a non-woven fabric and mentions on page 7 that a non-ionic wetting agent in the application formulation is desirable to provide absorbent characteristics to the fabric.
U.S. Pat. No. 6,017,561 relates to an antibacterial cleaning composition comprising a quaternary ammonium compound, an anionic polymer having an acid number greater than 10 wherein the anionic polymer is partially or completely neutralized by quaternary ammonium compound to form a polymer complex and wherein the polymer complex is greater than about 15% by weight of the solids in the composition, a dispersing agent, which comprises a surfactant that is selected from the group consisting of nonionic surfactant, amphoteric surfactant, and mixtures thereof, and optionally, a solvent. Also disclosed is a sponge device having antibacterial activity that comprises a sponge; and a polymer complex comprising a quaternary ammonium compound and an anionic polymer having an acid number of greater than 10 wherein the anionic polymer is partially or completely neutralized by the quaternary ammonium compound to form the polymer complex which is attached to a surface of the sponge. An adsorbent or absorbent matrix which includes the polymer complex and a method of fabricating an absorbent or adsorbent material which uses at least a quaternary ammonium compound and an anionic polymer are also disclosed. The ammonium compound may be PHMB hydrochloride. Articles such as sponges are also described.
U.S. Pat. No. 6,160,196 relates to a wound covering comprising a hydrophobic, bacteria-absorbing synthetic or naturally-occurring polymer fiber material, having adhered thereto an antimicrobial active compound which is adapted to not be released into the wound. As described in the specification and included in certain dependent claims, the material can be nonwoven and dependent claim 10 recites that the polymer fiber material can be selected from a group which includes polyester. The antimicrobial active compounds are described in the passage that begins at column 2, line 29 and include chlorhexidine. In this passage, it is stated the compounds “ . . . are distinguished by the fact that they adhere firmly to the wound covering and are not released, or at least are not released noticeably, into the wound.”
U.S. Pat. No. 6,180,584 relates to a disinfectant composition comprising a film-forming antimicrobial material (which may be a polymeric biguanide material), an antimicrobial metallic material, and a carrier. The composition, when applied to a surface, forms a non-permanent, adherent, water-insoluble film, wherein the metallic material is non-leachably bound to or associated with the film. The film does not elute antimicrobial materials into contacting water at levels capable of imparting disinfecting action to said water, and is removable by treatment with an alcohol solution. The composition can further include a surfactant.
U.S. Pat. No. 6,235,302 relates to a sponge cloth which is based on regenerated cellulose and has been provided with an internal reinforcement consisting of, e.g., viscose fibers or cotton fibers having a staple fiber length of 5 to 50 mm. The sponge cloth is obtained by a process comprising the steps of coagulating and regenerating the cellulose in a bath which has a pH of 13 or higher and which comprises Glauber's salt, NaOH and water, and impregnating the sponge cloth with a biocidally active agent. Representative agents are described and include isothiazolone, benzoisothiazolone and benzimidazole derivatives with biguanides.